1. Field of the Invention
The current invention relates to methods of making foraminous, or porous, microstructures, and in particular to methods of making foraminous films for use in photonic or plasmonic applications.
2. Background Information
The current major challenge in the fabrication of photonic structures is in creating structures with sufficient precision and good scalability. Hitherto man-made photonic structures have been fabricated by one of two commercial techniques. The first technique is based on a family of vapor deposition techniques for constructing photonic coatings on mirrors and lens. These vapor deposition methods usually entail sophisticated and expensive vacuum equipment and control systems. The other technique is the fiber draw technique. This technique does not entail vapor deposition processes, but is exclusively limited to the fabrication of photonic crystal fibers.
Other non commercial methods for photonic structures are available. One widely used approach is based on sophisticated micro-fabrication methods derived from microelectronics and laser beam writing techniques; however, these methods are usually either labor-intensive, expensive or complex and are not commercially used. Other common methods under development include electrochemical etching, layer-by-layer assembly, sol-gel deposition, block copolymer phase separation and colloidal self-assembly. However, electrochemical etching method only applies to single crystal semiconductor wafers, and the other methods are inconvenient to achieve for instance continuously modulating photonic structures with high resolution. The colloidal self-assembly involves using self-assembled colloidal nanobeads as templates, however, this approach is subject to the structural defects inherent in the template, and lacks flexibility in designing structural features other than those molded by the closest packed nanobeads.